Joiner s clamp



UNITED STATES ATENT Orrrcn,

FRANK MARTIN, OF OINOINNATI, OHIO.

JOlNERS CLAMP.

SPECIFICATION forming part of Letters Patent No. 484,104, dated October11, 1892.

Application filed November 2, 1891. Serial No, 410,567- (No model.) V ITo all whom it may concern.-

,Be it known that I, FRANK MARTIN, a citizen of the United States,residing at Cincinnati, in the county of Hamilton and State of Ohio,have invented new and useful Improvements in Joiners Clamps, of whichthe following is a specification.

My invention relates to bar-clamps, such as are used by joiners,machinists, and others, for the various uses for which the same areapplicable; and it consists in the clamp embodying certain elementsconstructed and combined in a novel manner, as hereinafter more fullyset forth, embracing a holding-bar provided with two clamping heads orjaws adjustable thereon, one of which is readily adjusted to ultimatepositions by hand and engages by pressure from the opposite head throughthe object clamped. The other clamping-head is engaged and controlled bya screw operated through a fixed head by means of a crank.

The principal feature of novelty in the present invention relates to theconstruction and arrangement of what may be termed the backing head orjaw of the clamp, by which its hand-adjustment upon the holding-bar isgreatly facilitated, and its engagement at any point without backlash orlost motion is secured.

Mechanism embodying my invention is illustrated in the accompanyingdrawings, in which Figure 1 is a side elevation of the device complete;Fig. 2, a rear View of the backing head, andFig. 3 a detachedperspective view of the holding-pawl.

Referring now more particularly to the drawings, A designates theholding-bar; B O, the adjustable clamping heads or jaws; E, the fixedhead; D, the adj usting-screw, and F the manipulating-crank. Theholding-bar A is preferably a thin bar of steel of rectangularcross-section and plane surfaces. The three heads B, O, and E referredto may be of cast iron or steel and are formed to embrace the bar A-thetwo former so as to slide freely thereon, while the latter is securedthereto by a single central rivet passed from outside to outside throughthe bar A, as shown at a. The construction and mode of combination ofthe clampinghead O, the screw D, and the fixed head E do not differmaterially from the ordinary practice.

The independent clamping-head or backing head B is constructed andarranged as follows: The rectangular slot by which it embraces the bar Ais extended upward to re ceive a rectangular friction-block P, whoseunder surface may be crossed and covered by dentate grooves, asindicated in Fig. 3. The head is also provided with a cross-opening b,as shown in Fig. 1, adapted to receive an eccentric pawl or cam 0,provided with a handle c, and engaging the friction-block P by means ofthe surface groove d, as clearly shown in the drawings. The handle 0'projects downward outside and is engaged and held forward by a' spring3, backed against a suitable projection, as b, of the headBat the sideof the bar A, whereby the pawl is always held in readiness for action.The arrange ment of these parts, as will clearly appear by reference toFig. 1, is such that any backward pressure upon the backing-head Boperates through the cam c to force the friction-block P directlydownward upon the holding-bar A, and if the pressure be excessive wouldembed the projections of its dentate surface into the upper face of theholding-bar. It will also be seen that by placing the fingerssay, of theleft hand behind the projection b and the thumb against the outside ofthe handle c' and compressing these two together the friction-blockPwould at once be released and the head B readjusted to any desiredposition upon the holding-bar A without removing the hand.

It will be seen that all the parts described may be cast and fittedtogether with very little expense and labor, excepting the holdingbar,which is cut from the ordinary merchant bars of rolled steel.

I claim as my invention and desire to secure by Letters Patent of theUnited States- 1. In a joiners clamp, an integral clamping or backinghead provided with a slot adapted to embrace and extend above theconnecting-bar and with a lateral opening extended through the sidechecks of the slot, in combination with a friction-block riding upon theconnecting-bar within the slot, and an echead and the friction-blockwithin the slot,

and a spring operating upon and holding said I 5 pawl or cam normallyengaging the clampinghead and friction-block, substantially as setforth.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing 20 witnesses.

FRANK MARTIN.

Witnesses:

L. M. HOSEA, E. HOSEA.

